This application is related to and claims priority from Japanese Patent Application No. Hei. 11-189407 filed on Jul. 2, 1999, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to an evaporator of a refrigerant cycle, in which a refrigerant distribution can be suitably set. The evaporator is suitable for a vehicle air conditioner, for example.
2. Description of Related Art
A refrigerant evaporator 110 having refrigerant passages shown in FIG. 19 is proposed in JP-Y2-2518259. The refrigerant evaporator 110 has plural tubes 100 each of which has two parallel refrigerant passages 100a, 100b therein, and first and second tanks 101, 102 formed independently from the tubes 100. One side refrigerant passage 100a communicates with the first tank 101, and the other side refrigerant passage 100b communicates with the second tank 102. A partition plate (not shown) is provided at a middle position of the first tank 101 in a tank longitudinal direction, so that the first tank 101 is partitioned into an inlet tank portion 101a for distributing refrigerant into the tubes 100 and an outlet tank portion 101b for collecting refrigerant from the tubes 100. The first tank 101 is disposed at an upstream side from the second tank 102 in an air flowing direction A. Further, a refrigerant inlet 103 is provided in the inlet tank portion 101a, and a refrigerant outlet 104 is provided in the outlet tank portion 101b. The refrigerant passage 100a defines upstream passages F1 and F4 provided at an upstream air side, and refrigerant passage 100b defines downstream passages F2 and F3 provided at a downstream air side.
In the evaporator 110, refrigerant from the refrigerant inlet 103 flows through refrigerant passages in a refrigerant flow direction shown by arrows in FIG. 19, and is discharged to an outside from the refrigerant outlet 104. When gas-liquid two-phase refrigerant flows toward the left side within the second tank 102 in FIG. 19, liquid refrigerant readily flows toward the leftmost side within the second tank 102 due to the inertia force rather than gas refrigerant. Therefore, a liquid refrigerant ratio becomes higher at a left side of the refrigerant passage F3, and the temperature of air blown out from the evaporator 110 becomes ununiform.
In the conventional refrigerant evaporator 110, throttle means is provided at the left side of the second tank 102 in FIG. 19, so that the quantity of the liquid refrigerant flowing toward the leftmost side of the second tank 102 is smaller in the evaporator 110, refrigerant almost gasified in the refrigerant passages F1, F2 flows into the refrigerant passages F3, F4 on the left side in FIG. 19, and air passing through the tubes 100 around the refrigerant passages F3, F4 is difficult to be cooled. As a result, in this case, a temperature difference of air blown from the evaporator 110 becomes larger between left and right sides.
In view of foregoing problems, it is an object of the present invention to provide an evaporator having a uniform temperature distribution of blown-air.
According to the present invention, in a refrigerant evaporator, a plurality of tubes are arranged in parallel with each other in a width direction perpendicular to a flow direction of air (outside fluid) and are arranged in plural rows in the flow direction of air, and plural tanks are disposed at both upper and lower ends of each tube to have upper tank portions and lower tank portions. The tanks are arranged to correspond to the arrangement of the tubes in the plural rows in the flow direction of air. The tanks have an inlet through which refrigerant is introduced, and an outlet through which refrigerant having passed through the tanks and the tubes is discharged. The inlet and the outlet are provided at side ends of the tanks in the width direction to be positioned at different-row tanks in the flow direction of air in such a manner that refrigerant Introduced from the inlet passes all refrigerant passages provided in one row where the inlet is positioned, passes through all refrigerant passages at adjacent row in order, and flows into the refrigerant outlet. In the evaporator, the lower tank portion has therein a throttle at which a refrigerant passage area is reduced. Thus, liquid refrigerant distribution in the tubes can be adjusted using the throttle, and temperature distribution of air blown out from the evaporator can be made uniform.
Preferably, the throttle includes plural throttle plates having throttle holes. Therefore, even when refrigerant distribution of the tubes in one row is ununiform, it is possible to offset the ununiform refrigerant distribution in a tube-overlapped portion in the flow direction of air, by suitably setting arrangement positions of the throttle plates,
More preferably, adjacent tanks adjacent to each other in the flow direction of air are partitioned by a partition wall, and are provided to communicate with each other through communication holes provided in the partition wall. Therefore, the refrigerant distribution of the tubes can be finely set using both the throttle holes and the communication holes.